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Quote, originally posted by Wikipedia » Hawk-Eye uses six or more television cameras situated around the ground, linked to a computer system. The computer reads in the video in real time, and tracks the path of the ball on each camera. These six separate views are then combined together to produce an accurate 3D representation of the path of the ball, which can be viewed in a virtual reality simulation.
More here: http://www.hawkeyeinnovations....e.htm